Q: What is the recommended pretreatment for a desalinatin unit going in yachts and cruise ships? It is made of aluminum. Currently being sandblasted and 4 to 6 mils of TGIC powder applied. I want to recommend chem film to replace the blast and feel 2 to 3 mils of coating would be sufficient. Thanks.

A: Without knowing more about the design and fabrication of the desalination unit made of aluminum, I would agree that the application of a chromate conversion coating, such as ChemFilm would be appropriate. However, I do not believe that 2-3 mils of TGIC is necessarily adequate. First, I'm not sure that TGIC is the most appropriate resin for this application, and secondly I would consider applying a zinc-rich primer under the topcoat. You might want to call powder coating companies and get a recommendation for the primer/topcoat combination.